Final Exam ALR & P300 Flashcards
(118 cards)
1
Q
What are ALR’s?
A
Auditory Late Response (ALR)
* are cortical responses that are evoked by the presentation of auditory stimuli and processed in or near the auditory cortex
2
Q
What affects ALR’s?
A
- Age (neuromaturation)
- Sleep - patients need to be awake and alert
- Drugs affecting the CNS
- Auditory training
3
Q
ALR
P1-N1-P2 complex is considered an ____ response of the brain meaning that if sound reaches the neural generators of these waveforms, the response will occur
A
P1-N1-P2 complex is considered an obligatory response of the brain meaning that if sound reaches the neural generators of these waveforms, the response will occur
4
Q
P1, N1 & P2 are endogenous or exogenous?
A
- P1-N1-P2 complex is considered an obligatory response
- This complex is an exogenous event-related potential (ERP) - no internal process
5
Q
Whata are the components of the ALR and there latency?
A
P1 or P50: 50 ms
N1: 100ms
P2: 200 ms
N2: 250 - 275 ms (first endogenous component)
6
Q
In ALR’s what is the largest component in children?
A
P1/P50
* Earliest positive component
7
Q
In ALR’s what is the largest component in adults?
A
P2
* Largest in Adults & older children
* Amplitude in adults is ~ > 3 to 10 uv, but may be absent in young children due to neuromaturation
8
Q
What is the first endogenous component?
A
N2
* May not always be present in adults so not given much importance
9
Q
Some components of the ALRs are exogenous and others are endogenous. List them and the mental process.
A
- P1,N1 & P2 are exogenous potentials
- N2 is the first primarily endogenous potentials -nonspecific polysensory system in the supratemporal auditory cortex
10
Q
Name the ALR Neural Generators.
A
- Precise location of the ALRs neural generators is unclear
overlapping ALR neural generators can include - primary and secondary auditory cortices
- Posterior superior temporal plane
- Lateral temporal lobe
- Frontal motor and/or premotor cortex
11
Q
ALR Subject state for recording responses
A
Best Responses
* Adults or children > 6 yrs old
* Awake, alert, eyes open, reading, watching close-caption TV
12
Q
In ALR’s for infants and young children, the most prominent wave is what?
A
infants and young children, the most prominent wave is a large positive component, the early P1
13
Q
ALR
What age is P2 mature by?
A
- P2 wave is essentially mature by age 2 to 3 years
- becomes larger and sharper with maturation
14
Q
ALR
At what age does N2 first appear?
A
N2 first appears at ~3 years of age
* latency of ~280
15
Q
ALR
at what age is N2 adult like?
A
reaches adult latency of ~250ms by about 12 years
16
Q
ALR montage?
A
Same as ABR
17
Q
ALR Recording Parameters
Filters:
Stimuli:
Rate:
A
- Filters: <1 (high pass) to 100 (low pass)
- Stimuli: speech-like stimuli or 250 to 4000 Hz tone bursts
- Rate: < 1 / sec (0.5 is recommended)
- Faster rates show reduction of the waveform amplitudes
18
Q
Does Rate have a large affect on ALR’s?
A
- Rate (it has a profound effect on the late responses)
- Less than 1/s
- Faster rates show reduction of the waveform amplitude
19
Q
Can you get ALR’s with a child younger than 6 who is awake and quiet?
A
Possible responses
* ideal is 6+
* Awake, alert, eyes open and reading, watching TV etc
20
Q
ALR’s Waveform must be _ to _ times larger than average amplitude of the ____
A
Waveform must be 2 to 3 times larger than average amplitude of the pre-stimulus
21
Q
What ALR responses are typically measured for awake and alert patients > 6-years-old
A
- N1 latency
- N1-P2 amplitude
22
Q
ALR Response measured for sleeping adults
A
Very Large N2
Odd? since its endogenous
23
Q
ALR Response measured for awake young children
A
Large P1
24
Q
What is the most important consideration for ALR’s?
A
Repeatability of stimulus tracing is the most important consideration for waveform analysis
25
26
____ of stimulus tracing is the most important consideration for waveform analysis
**Repeatability** of stimulus tracing is the most important consideration for waveform analysis
27
Normal variations of waveforms, ALRs ____ , _____ , and ____ vary considerably.
Normal variations of waveforms, ALRs **amplitude**, **morphology**, and **latency** vary considerably.
28
for ALR it is imporant to consider what as possible variation affects?
* Consider the effects of sleep
* age because of attention/neuromaturation effects.
29
What is Considered an abnormal ALR response?
* reduced Amp
* Polarity reversal for selected components
* Total absences of one or more
* Prolonged Latency (variable)
* Absent N1 - P2
30
ALRs are usually seen as two distinct components, what are they?
N1-P2 or the N1 component
P2-N2 or the N2 component
31
How is Amplitude typically measured, typically in ALRs?
Amplitude is measured, typically, from **peak-to-peak** of ALRs components
* N1-P2 peak amplitude measurement is ~10.7 μV
* P2 amplitude ~7 μV
32
For ALR's what affects amplitude?
* amplitude of the response changes with both **stimulus** condition and **pathology**
* ↓amplitude = ↓ intensity
* But latency remains stable at > 20 dBSL
33
P1-N1-P2 of ALR is detected down to what?
1-N1-P2 complex is often detected down to **10 dB nHL**
34
# ALR
N1-P2 peak amplitude measurement is ~ ___ μV
P2 amplitude ~ ___ μV
N1-P2 peak amplitude measurement is ~ **10.7** μV
P2 amplitude ~ **7** μV
35
As intensity decreases to 10 to 15 dB SL what changes in P2 and N1?
* P2 is not longer seen
* N1 then becomes the lowest observable response
36
Clinical uses for ALR
Age & ALR's
* Age-related timing deficits have been reported for cortical speech-evoked responses (VOT) - as people age, the neurologicals system starts to degenerate.
* Younger adults maintained a learning curve and the rate of improvement increased when compared to older adults.
* Counseling and management should consider treatment options beyond providing audibility for older adults.
Slow acting compression algorithms may help older adults.
37
ALR Clinical Uses
* Age-related timing deficits have been reported for cortical speech-evoked responses
* Neuromaturtion and Auditory deprivation affects
* Pre- and post- auditory training change
* Schizophrenia identifcation
38
P1 changes with age so it is a what?
P1 changes with age so it is an **auditory biomarker of the developing auditory system** post-exposure to sound
39
For ALR's CI children showed normal P1 until what year of implatantion?
* Implanted < 3-years showed normal P1 responses within 3 to 6 months
* 1/2 the children implanted at 3.5 to 6.5 years showed normal P1 responses
* All the children implanted after 7-years showed abnormal P1 responses
40
Are ALR's Able to show you the difference pre and post amplification?
Yes
* pre amp = increased latency
* Post amp = decrased latnecy
41
Are ALR's Able to show you the difference pre and post Implantation?
Yes
* pre implant = absent P1
* Post Implant = Present P1
42
Can ALR's show auditory training improvment?
Yes
* Pre- and post- auditory training changes were noted in the ALR, **N2 latency decreased, and P2-N2 amplitude increased.**
* No changes in ABR
43
Can ALR's show difference between (C)APD, LD, and ADHD?
NO ALRs cannot distinguish between ADHD, CAPD, and LD
44
The latency of the what response can serve as biomarker for maturation of central auditory pathways post HA/CI use
The latency of the **P1** response can serve as biomarker for maturation of central auditory pathways post HA/CI use
45
# ALR
P1 is a good biomarker for outcomes of HA and CI management for children with what?
P1 is a good biomarker for outcomes of HA and CI management for children with **ANSD**
46
For Children with ANSD what would there ALR look like if they would benefit from HA's?
Children who showed a **normal or delayed P1** had some dys-synchrony → These children benefitted from HAs
47
For Children with ANSD what would there ALR look like if they would **not** benefit from HA's?
Children who had **abnormal or absent P1** had greater dys-synchrony
* These children did not benefit from HAs
* These children would probably benefit from a CI
48
For Children with ANSD what would there ALR look like if they would benefit from CI's?
Children who had **abnormal or absent P1** had greater dys-synchrony
* These children did not benefit from HAs
* These children would probably benefit from a CI
49
What test and wave P1 is a biomarker of auditory neuromaturation and can be used to make management decisions for children with ANSD
ALR's, P1
50
Is there a sensitive period to implant children with ANSD?
YES
* Children implanted **before 2 years** showed a better P1 response than children implanted after 2 years
51
What is Schizophrenia?
Schizophrenia is a severe, chronic, and generally disabling cognitive and behavioral disorder
* It is a psychosis, a type of illness that causes severe mental disturbances that disrupt normal thoughts, speech, and behavior
52
What causes Schizophernia?
a combination of genetic and environmental factors
* It occurs in 1% of the general population but in 10% of people with first degree relatives
53
Why is ALR good tool for assessing schizophrenia?
Disordered cognition is considered the core symptom of schizophrenia, which makes the ALR a good tool to assess these patients
54
Are ALR's Able to identify Schizophrenia?
Yes
* Decrease in N1 amplitude with a slight increase in latency
* Suppression of S2 or sensory gating does not occur suggesting subcortical dysfunction of the thalamus
55
What does Schizophrenia look like in ALRs?
* Decrease in N1 amplitude with a slight increase in latency
* Suppression of S2 or sensory gating does not occur suggesting subcortical dysfunction of the thalamus
56
why more are ALR still infrequently applied in the clinic?
* grad students are given little formal class teahing
* gap between the research and clinical app
* variability within normal individuals
* No billing code
57
The P300 occurs as a result of what?
P300 occurs as a result of higher level internal brain processing assocaited with stimuluss recognition and novetly
58
The P300 occurs as a result of higher-level internal brain processing associated with stimulus ____ and __
It occurs as a result of higher-level internal brain processing associated with stimulus **recognition** and **novelty**
59
P300 is endogenous or exogenous?
It is classified as an **endogenous response**
60
The P300 is referred to as a ____ response or a reflection of ____ to a stimulus
The P300 is referred to as a **cognitive** response or a reflection of **attention** to a stimulus
61
In normal subjects the P300 range is ___ ms
In normal subjects the P300 range is **250 to 400 ms**
62
what do they mean by The P300 is nonsensory specific response?
The P300 is a brain response that reflects recognition, attention, or decision-making, not just raw sensory input
63
what are Neural generators for the P300?
Multiple overlapping sites
* Primary Auditory Cortex
* Frontal & Temporal Cortex
* Temporopariertak associarion cortex
* Hippocampus
* Limbic System
* Cingulate gyrus
64
What is the most common stimulus condition to elicit the p300?
the “oddball” paradigm
* standard stim 80% of time and oddball stimulus ~ 20%
* Presented randomly
* Count add balls,
65
# true or false
In the p300 background sounds/noise reduce the amplitude of the P300
FALSE
Background sounds/noise does **not** appear to reduce the amplitude of the P300
* But increased intensity does appear to increase the amplitude
66
The P300 can be shown to have two components with the appropriate stimulus. P3 a & p3b how do you elicit it?
for P3a and P3b, a **three-tone oddball** paradigm is used
* A standard stimuli
* A rare target stimuli
* A rare non-target stimuli
67
what is a three-tone oddball paradigm and what is it used for?
three-tone oddball paradigm
* A standard stimuli
* A rare target stimuli
* A rare non-target stimuli
Use
* elicit the P3a and P3b
68
with the three-tone oddball paradigm how do you get the P3a?
The listener is NOT asked to pay attention to the *rare non-target* stim = P3a
* it reflects: Automatic, involuntary attention shift (your brain notices something is different, even if you're not actively listening for it)
69
with the three-tone oddball paradigm how do you get the P3b?
The listener IS asked to attend to *rare target stim*
* it reflects: Active attention and stimulus evaluation (you’re intentionally listening for and recognizing the rare target)
70
# P300
If you ignore a rare non-target sound, you get ____
If you pay attention to a rare target sound you get ___
If you ignore a rare sound, you get **P3a**.
If you pay attention to a rare sound you're told to listen for, you get **P3b**.
71
Where are the p3a neural generators?
at least partial neural generators in the **prefrontal lobe**
72
Where are the p3b neural generators?
Temporal/Parietal lobe
73
What part of the P300 is active and which is passive?
Passive → P3a
* occur in response to changes of either the attend or nonattentive stimuli
Active → P3b
* only elicited in response to effortful attention
74
When does the target response occur in the P300?
A target response occurs when listeners are asked to “count” for the deviant sound and the nontarget deviant is unexpected
* greater the difference between the standard and nonstandard stimuli the larger the amplitude of the P3 complex
75
What determines that amplitude of the P3 complex?
greater the **difference between the standard and nonstandard stimuli** the larger the amplitude of the P3 complex
76
P300 Recording Parameters
Stimulus:
Spectral power region:
Epoch:
Rate:
Filter: 0.5-1 to 100 Hz
Polarity:
Intensity:
* Stimulus: “Oddball” paradigm
* Tonal signals: 2000 Hz target, 500 Hz oddball (infrequent)
* Spectral power within the region 1 to 15 Hz
* Epoch: 500+ ms
* Rate: < 1.1 / sec
* Filter bandpass: 0.5-1 to 100 Hz
* Polarity: alternating
* Intensity: < 70 dB nHL
77
Spectral power of normal auditory late responses, including the P300, is within the region of what?
Spectral power of normal auditory late responses, including the P300, is within the region of **1 to 15 Hz**
78
What's the P3 amplitude?
P3 is a large, broad, long latency response with an amplitude of **~ 10 to 20 µv**
79
P3 is described in terms of what components?
latency and amplitude, with amplitude being more sensitive
80
variability for the P300 latency is related what?
* stimulus parameters
* task difficulty
* subject factors such as age, alertness, attention, and cognitive status
81
How are P300 abnormalities are reported?
P300 abnormalities are reported in terms of **decreased latency, reduced amplitude, and abnormal or absent waveforms**
82
What Factors affect the P300?
* Age (neuromaturation)
* Drugs that affect the CNS
* Disease conditions
* Attention
During recording patients need to be awake and alert
83
How does Age (neuromaturation) affect the P300?
* “adult-like” by about 15 years
* Do not perform 6 yrs and younger
* Less reliability with advancing age (system degrades is older adults, and cognitive issues arise)
84
What age is the P300 adult like?
~15 yrs
85
How does Attention affect the P300?
P300 is an endogenous response and, therefore, affected significantly by the listener’s ability to attend to the oddball stimulus
* Absence of a P3 could be due to individual’s inattention to the rare stimulus rather than an ability to process sounds
86
Absence of P3 when alertness is *not* questionable may be evidence of what?
Absence of P3 when alertness is not questionable may be evidence of **higher-level CANS dysfunction such as dementia**
* P3a can be elicited without the listener actively attending to the oddball non target stimulus
87
How do drugs affect the P300?
Drugs that affect the CNS - any depressants or excitatory drugs will vary results
* Anesthetic drugs: some affect latency, and some amplitude
* Sedatives and tranquilizers: can affect ALR and P300 response.
* Drugs that produce central suppression of brain activity will significantly influence and usually diminish the ALRs & P300 (Barbiturates)
* Acute alcohol intoxication can decrease the amplitude of ALR and P300 responses
88
Acute alcohol intoxication = what ALR response
decrease the amplitude of ALR and P300 responses
89
Anesthetic drugs = what ALR response
different effects on different ALRs
Some **affect latency and other amplitude**
90
Sedatives and tranquilizers = what ALR response
Sedatives and tranquilizers: can affect ALR and P300 response.
* diazepam and Librium
91
Drugs that produce a central suppression of brain activity = what ALR response
significantly influence and usually diminish the ALRs & P300
* Barbiturates
92
Barbiturates = what ALR response
Barbiturates produce a central suppression of brain activity
* significantly influence and usually **diminish the ALRs & P300**
93
Chronic alcoholic = what ALR response
depress your P300 - it is a CNS depressant - decrease as an auditory and visual response
* More decrease for male alcoholics.
94
Chronic Alcoholism affects on P300
decrase your P300 amplitude - it is a CNS depressant - decrease as an auditory and visual response
* More pronounced male alcoholics.
* low amplitude P300 exhibited by alcoholics indicates less CNS inhibition than controls
* P300 reflects CNS inhibition : larger amplitude = great inhibition
* Alcohol makes your system more excitable - alcohol inhibits your system so all that is left is the excitation
95
fMRI shows inefficient brain functioning in alcoholics in the critical areas of what?
fMRI shows inefficient brain functioning in alcoholics in the critical areas where P300 originates
* Frontal cortex: executive function
* Hippocampus: consolidating new memories
* Amygdala (limbic system): producing and controlling emotional behavior
95
The Larger the p300 the =
The Larger the p300 the greater the inhibition
* The low amplitude P300 exhibited by alcoholics indicates less CNS inhibition than controls
96
Alcohol is a CNS ___
Alcohol is a CNS **inhibitor**
97
AEP differnces in CAPD
* ABR
* AMLR
* ALR
* ABR did not appear to be a useful diagnostic tool
* AMLR and ALR's were sensitive to the suspected (C)APD in the children with learning difficulties
CAPD and LD - more research is needed to establish clinical criteria
98
for P300 Alzheimer’s patients, with age-adjusted responses show what?
* Decrease in both amplitude and latency of P300
* identity mild and moderate AD
* potential for earlier diagnosis of AD and better outcomes
99
P300 can identify what form of Alzheimer’s?
P300 can identify **mild and moderate AD**
* P300 cannot identify severe AD
100
what do P300's look like for Patients with Schizophrenia?
* Shows **decreased amplitude**, fluctuates as the disease does with symptoms
* **Prolonged latency**
* No relation between P300 and duration of schizophrenia
101
what do P300's look like for Patients with Type 2 diabetes?
| w/normal hearing
* Decreased amplitude
* Increased latency
when blood glucose was high immediately before testing:
* Only amplitude was affected:
102
what do P300's look like for Patients with Language related responses?
these Responses appear specific to language comprehension
* **N400**: response to semantically inappropriate words (does not make sense in the sentence)
* **P600**: syntactically anomalous word within a sentence (the structure of the sentence is not right)
103
# True or False
MMN is a preattentive stimulus
TRUE
* MMN reflects the brain’s unconscious detection of a difference (i.e., mismatch) process between the sensory inflow created by the deviant stimulus and the memory trace of the standard stimulus
* Occurs without needing the listener's attention → it is preattentive
104
How is MMN observed?
MMN is observed by subtracting the brain’s response to the standard from the response to the deviant (oddball stim)
105
MMN Latency
latency region of around 100 to 300ms
106
MMN responses are
* automatic
* Not confounded by attention & cognitive factors
* observed even when not involved in counting task
107
MMN can be seen as an...
Can be seen as an **enlarged N1, second negative peak, or attenuation of the P2 peak**
108
MMN Neural Generators
* primary Aud Cortex (suprtemporal plane)
* Frontal Lobe
* Subcortical regions of the auditory system
109
MMN is best visualized as a ___ waveform
MMN is best visualized as a **difference** waveform
110
what are the most common measured parameters of the MMN
**Amplitude and latency** are the most common measured parameters of the MMN
111
MMN is not affected by ___ or ___ and can be recorded during REM sleep
MMN is not affected by **sleep** or **attention** and can be recorded during REM sleep
112
# True or False
MMN amplitude and latency variations are common across and present 70% of the time.
FALSE
MMN amplitude and latency variations are common across and within normal subjects and it may be absent in about half of normal listeners
113
MMN recording parameteres
same as the ALR and P300
* Epoch = 100 to 400 ms
* MMN also has very low frequency energy
114
MMN Recording Challenges
* No test protocol that is brief and reliable
* Enhancement of the signal to noise ratio for the reliable detection of the MMN wave
* Proven analysis strategies to statistically assure the presence of a response
* Improved reliability of MMN recording in a clinical setting across various patient populations including young children
* Poor SNR (cannot detect response)
* Inter and intra-subject variability
* Not recorded from all normal adult subjects
* Technical challenges to reliability interpret a response
115
Clinical applications
* Processing abilities of CI patients
* Study of CAPD
* Evaluation of patients who are comatose
* Aging population
* Parkinson's disease, and Dementia patients
116
Clinical applications are limited significantly by
* Poor SNR, which makes response detection difficult
* Inter- and intra-subject variability
* May not be recorded from all normal adult subjects
* Technical challenges to reliably interpret a response
117
Difference Between MMN and P300
